Bivalvia, in previous centuries referred tae as the Lamellibranchiata an Pelecypoda, is a cless o marine an freshwatter molluscs that hae laterally compressed bouks enclosed bi a shell conseestin o twa hinged pairts. Bivalves as a group hae na heid an they lack some uisual molluscan organs lik the radula an the odontophore.

↑Jell, Peter A. (1980). "Earliest known pelecypod on Earth — a new Early Cambrian genus from South Australia". Alcheringa: An Australasian Journal of Palaeontology. 4 (3): 233–239. doi:10.1080/03115518008618934.